The present invention is directed to a printing unit including a forme cylinder and a transfer cylinder. A satellite cylinder cooperates with the transfer cylinder to provide a print location.
A printing press is known from EP 0 644 048 B1. Pairs of cylinders, each consisting of a forme and a transfer cylinder, are mechanically fixedly coupled. Each cylinder pair has its own drive motor. The cylinder pairs themselves cannot be coupled to each other.
DE 44 30 693 A1 discloses printing units of a printing press with separate configurations of cylinders which are driven individually or in groups. Cylinders, or groups of cylinders are not in a driven connection with each other.
A four-cylinder printing unit is known from DE 196 03 663 A1. Two transfer cylinders, which cooperate with each other, are fixedly coupled to each other and can be selectively driven by the drive mechanism of one or of both associated forme cylinders. In one embodiment, a pair of cylinders, consisting of a forme cylinder and a transfer cylinder, which can be driven at the forme cylinder, can be placed against this four-cylinder printing unit, and can be coupled into the drive assembly between the two first mentioned transfer cylinders for synchronization, or correctly registered printing.
EP 0 710 558 A1 discloses two printing towers, each of satellite construction, of mechanically coupled forme and transfer cylinders arranged in pairs, which are driven by a common motor. A web can be passed through both printing towers. In case of a change in production, one printing tower is taken out of operation while the other printing tower continues to print.
A drive mechanism of a printing unit for a flying plate change is known from EP 0 243 721 A2. The driving takes places from a main drive fixed against relative rotation to the counter-pressure cylinder. Forme and transfer cylinders, mechanically coupled in pairs, can be selectively coupled via a switchable connector with the driven counter-pressure cylinder.
The object of the present invention is directed to providing a printing unit.
In accordance with the present invention, this object is attained by the provision of a printing unit having a cylinder pair comprised of a forme cylinder and a transfer cylinder. A satellite cylinder cooperates with the transfer cylinder to form a print location. The forme cylinder drive and the transfer cylinder drive are coupled together during printing and are driven by a common drive motor. A drive mechanism for the satellite cylinder can be selectively switched via a switchable coupling or connector and can be mechanically coupled with the drive assembly for the cylinder pair.
The advantages which can be gained by the present invention lie, in particular, in that a great operational diversity and variability of a printing unit or of compound cylinders, along with a high degree of operational dependability, is provided, without each cylinder being provided with its own drive mechanism. The present invention combines the advantages of the substantial flexibility afforded by the expensive and elaborate single drive technology, with the advantages of coupled cylinder groups, namely the savings of motors and the mechanical synchronization of the connected cylinders.
As a rule, by the provision of the advantageous arrangement of switchable couplings and motors in accordance with the present invention, as many of the desired operating modes are possible as would be the case with the embodiment where all cylinders are provided with separate motors. Thus, with the coupling released, it is possible to move cylinders, or groups of cylinders, independently of each other, which is required, for example, when the printing formes or rubber blankets are exchanged, when a paper web is drawn in, or when rollers and cylinders are independently inked or washed. In many cases, an auxiliary drive mechanism can be omitted, since the function of this auxiliary drive mechanism can be taken over by the main drive mechanisms, if the couplings are appropriately switched. In the same way, is it possible to perform the switching of individual cylinders or cylinder groups of connected larger cylinders, in that new drive assemblies are formed by releasing couplings and by activating other couplings.
Moreover, a substantial advantage lies in the option of standardizing individual small groups, which meet the above mentioned requirements, for example a pair of cylinders consisting of a forme cylinder and a transfer cylinder with an appropriate coupling, and of combining these standardized small groups in any desired way, depending on the request made in the purchase order, into larger units. An above mentioned cylinder pair with a coupling can also represent a standard group, together with a counter-pressure or satellite cylinder. The journals of the cylinders can be configured as required, for example selectively with or without coupling, or with a gear wheel which can be fixed against relative rotation or can be fixed in place, and matching a first or second drive level.
In particular, in connection with printing units which can be switched from rubber-on-rubber to rubber-on steel operation, i.e. printing units in which at least one of the transfer cylinders can be selectively placed against a satellite cylinder or a second transfer cylinder, a reversal of the direction of rotation of one or several cylinders becomes necessary, depending on the unit. With a five-cylinder printing unit, an embodiment with one drive motor per pair of forme and transfer cylinders is advantageous, in which the satellite cylinder can be coupled with one of the two or with both drive motors, or pairs, depending on the paper guidance path and the mode of printing unit operation. For a seven-cylinder y- or lambda unit, which can be flexibly employed, for example, for a 3/0, or a 2/1 production run, the flying plate change, or during the imprint function in the course of 1/1 printing, an embodiment with only a total of two drive motors is sufficient for all requirements. Moreover, a 1/0 and a 1/1 production run is possible during two-web operations.
The present invention can also be employed particularly advantageously and efficiently in nine-cylinder or in ten-cylinder printing units. In such units, maximum flexibility, along with a minimal number of motors, is required in view of the modes of operation to be met.
A minimum requirement, the independent fitting in pairs of the pairs of cylinders when a web has been drawn in, is realized with minimum outlay in an advantageous configuration. One, or several pairs of cylinders form a fixed drive assembly, and the satellite cylinder, which is embodied without its own drive motor, can be selectively coupled in or released.
The embodiment of each cooperating and fixedly coupled cylinder pair with a drive motor is advantageous here, wherein at least two of these pairs can be coupled with the satellite by use of a switchable connector. With the savings of two connectors, the embodiment with only two cylinder pairs switchably coupled to the satellite cylinder is advantageous in nine- or ten-cylinder printing units. In this way, the satellite can be driven by the respectively other coupleable pair during partial reversal or stopping of a pair.
The selective coupling of a fixed drive assembly of the cylinder pair with a counter-pressure cylinder is the basis of the previously discussed great variety of operating modes.
The substantial operational dependability provided because of the redundancy in the number of usable drive motors, is also advantageous in the case of several drive mechanisms which can be coupled by of connectors.